The recent post on "Screening Preferences" drew thoughtful comment.
It reminded me of a conclusion I reached while preparing a book on leadership. Although people sometimes speak of "putting a business executive in the White House," the transfer of lessons from the private sector to the public one is far more difficult than the reverse. The public sector's restrictions, combined with its multitude of second-guessers, possess factors that don't exist in private sector leadership. The lessons from the public sector - such as the handling of the Cuban Missile Crisis - can be more easily applied to private sector scenarios.
As for the reason why a Churchill or DeGaulle might have greater difficulty rising in a private sector firm, that may come from the tendency of private sector organizations to favor a particular type. Voters are more open to eccentrics and those who do not fit the mode although they do have their own bias. Political candidates who appear to be from Central Casting can seem too programmed even though they may have impressive records of achievement.